Locomotor strategies in obese and non-obese children.

OBJECTIVE: The constant strain in obese children may increase the risks of articular problems in adulthood. In the short term, obesity in children could lead to modifications of the gait pattern. The purpose of this study was to compare biomechanical parameters between obese and non-obese children during self-paced walking. RESEARCH METHODS AND PROCEDURES: Gait analysis was performed on 10 non-obese and 10 obese (body weight > 95th percentile) children between 8 and 13 years of age. Subjects were asked to walk at their own pace on a 10-m walkway with two embedded AMTI force plates (Advanced Mechanical Technology, Watertown, MA) sampling at 960 Hz. Kinematics were captured with eight VICON optoelectronic cameras (Oxford Metrics Limited, Oxford, United Kingdom) recording at 60 Hz.
RESULTS: Obese children modified their hip motor pattern by shifting from extensor to flexor moment earlier in the gait cycle. This led obese children to significantly decrease the mechanical work done by the hip extensors during weight acceptance and significantly increase the mechanical work done by the hip flexors compared with non-obese children. The ratio of power-absorption-by-hip-flexors to power-generation-by-hip-flexors was also significantly increased in the obese group compared with non-obese children. Finally, there was a significant decrease in the single support duration in the obese group compared with non-obese. DISCUSSION: The kinetics analyzed showed that obese children could take advantage of a passive hip strategy to achieve forward progression during walking. However, considering that they are mechanically less efficient to transfer energy, walking at a natural cadence should be an appropriate exercise to reduce weight in obese children.